Optical lens providing omni-directional coverage and illumination

ABSTRACT

The invention presents a wide-angle imaging assembly which comprises a main lens produced from an aspheric optical block. The aspheric optical block comprises a vertical axis of symmetry; a transparent upper surface, at least part of which is capable of reflecting rays that impinge upon it from the interior of the optical block; a transparent perimeter surface; and a transparent lower surface. The optical block is fabricated from material selected to enable optical transmittance of a specific spectral range. Light rays in the specific spectral range originating in a first scene, having a 360 degrees panoramic perimeter, are refracted by the transparent perimeter surface, enter the optical block, are then reflected by the upper surface towards the transparent lower surface, where they are then refracted by the transparent lower surface, and exit through it.

FIELD OF THE INVENTION

The present invention relates to the field of extremely wide-angleimaging. More specifically, it relates to optical structures that enablethe coverage and/or illumination of a panoramic or nearly sphericalfield of view, suitable for video or still imaging.

BACKGROUND OF THE INVENTION

Imaging of a large field of view has many applications in the fields ofdefense, security, monitoring, entertainment, industry, medical imagingand many other fields. Imaging of a panoramic or nearly spherical fieldof view, using a single image-capturing device, is especially applicablefor a variety of needs due to its relative simplicity, low-cost andminiaturization possibilities.

Security cameras often require the ability to view as large a field ofview as possible to enable imaging of all occurrences in a scene forpurposes of real-time surveillance and warning or for documentation andrestoration of images at later stages.

Inner body imaging during diagnostic or therapeutic medical proceduresrequires real time viewing of a large field of view in order to providethe surgeon with the ability to orientate and maneuver the medical scopewithin the body without endangering body organs or risk causing damageto body tissue. These applications also require the ability toilluminate the scene that is imaged in order to provide a clear andunderstandable image to the physician.

Additional applications, which require a large field of view exist,include remote operation of ground vehicles, imaging equipment forreconnaissance and information gathering, viewing the interior ofdevices such as engines, and cinematic and home entertainmentapplications.

One of the prior art techniques of panoramic imaging makes use ofseveral image capturing devices, each one aimed at a different sectorlimited in width, combined in a manner such that all of them together,when properly aligned, cover a full 360 degrees field of view. Anotherprior art method for panoramic imaging relies on a singleimage-capturing device, rotated around a vertical axis. In this methodthe image-capturing device covers a limited sector at any single moment;but, while completing a full rotation, it creates a sequence of images,which are combined together to form a panoramic image.

The main disadvantage of these prior art methods is their relativecomplexity. Some prior art methods make use of moving/rotatingmechanisms, which require frequent alignment and very often turn out tobe maintenance-intensive.

The ability to make use of a single imaging device, equipped with anoptical structure, which would enable viewing of the entire perimeteraround the imaging device, would be invaluable for the applicationsdescribed hereinabove.

A prior art approach using a single imaging device makes use ofaxi-symmetric reflective surfaces to reflect a panoramic field of viewtowards a single image-capture device. In this approach a circular imageis formed on the focal plane array of the image-capturing device. Theshape of the image derives from the reflection of the surrounding fieldof view by the reflective lens, and often includes aberrations. Theimage shape and additional aberrations are corrected by image processingtechniques. Such a prior art design is described in U.S. Pat. No.6,028,719, in which a method for capturing a nearly spherical field ofview using a single axi-symmetric reflective mirror with a hole in itscenter is described. The main disadvantages of the methods described inU.S. Pat. No. 6,028,719 include the relatively complex fabrication ofthe optical components to achieve high optical performance, the highfabrication costs of the imaging device and its sensitivity toenvironmental conditions. Furthermore, such devices provide relativelypoor image quality.

A simpler, cheaper and more robust solution for imaging and/orilluminating a panoramic or nearly spherical filed of view would be touse an aspheric optical block, a single image capturing device and insome embodiments—an illumination source. Attempts to fabricate such adevice have been made, e.g., in U.S. Pat. No. 6,341,044, which makes useof an optical block and a single image capturing device to providepanoramic imaging. The design used in U.S. Pat. No. 6,341,044 includes aspherical optical block having one refractive surface and one reflectivesurface. The spherical shape of the optical block and the existence of asingle refractive surface incorporated within the optical block itselfintroduce aberrations that must be corrected by several sets ofadditional optical lenses along the optical path, as describedextensively in the patent.

It is therefore an object of the present invention to provide an opticalblock designed to provide a reflection of a panoramic perimeter, havingan acceptable level of distortions and aberrations.

It is another object of the present invention to provide an opticalblock designed to enable acquiring of a nearly spherical field of view.

It is another object of the present invention to provide an imagingassembly, based on the optical block of the invention.

It is yet another object of the present invention to provide a method ofilluminating the scene that is imaged, simultaneously while imaging;utilizing the same optical block for both coverage of the scene and thetransmittance of illumination to the scene.

Further purposes and advantages of this invention will appear as thedescription proceeds.

SUMMARY OF THE INVENTION

The present invention provides a wide-angle imaging assembly comprisinga main lens produced from an aspheric optical block. The asphericoptical block comprises the following elements:

-   -   a. A vertical axis of symmetry;    -   b. A transparent upper surface, at least part of which is        capable of reflecting rays that impinge upon it from the inner        side of said optical block;    -   c. A transparent perimeter surface; and    -   d. A transparent lower surface.

The material of which the optical block is fabricated is selected toenable optical transmittance of light in a specific spectral range.

Light rays in the specific spectral range that originate in a firstscene which has a 360 degrees panoramic perimeter are refracted by thetransparent perimeter surface and enter the optical block. They are thenreflected by the upper surface towards the transparent lower surface,refracted by the transparent lower surface, and exit the main lensthrough the transparent lower surface.

The upper surface of the wide angle imaging assembly of the inventioncan be at least partially, axi-symmetrically coated with reflectivematerial on its exterior side. The reflective coating will causereflection of light rays that impinge upon the upper surface from theinner side of the optical block. The reflective material that coats theupper surface can be selected to enable reflection of light rays in thespecific spectral range transmitted by the material of the opticalblock.

The wide angle imaging assembly of the invention may further comprise atransparent area in a part of the upper surface around the vertical axisof symmetry. The transparent area enables light from a second scene,located at least partially above the first scene, to pass through thetransparent area and travel through and exit the optical block. Thecurvature of the surface of the transparent area can be different fromthe curvature of the remainder of the upper surface. The lower surfacecan be described by two different axi-symmetric curves.

The transparent area can be fabricated in the form of a hole extendingalong the vertical axis of symmetry. The hole can extend from the uppersurface to the lower surface and can have a conical shape. An opticalstructure designed to enhance or correct light rays coming from thesecond scene can be placed within the hole. The optical structure placedwithin the hole can comprise a plurality of optical components.

In another embodiment, the wide angle imaging assembly of the inventionfurther comprises an optical structure located above the transparentarea and coaxially with it. The optical structure is designed to enhanceor correct light rays coming from the second scene or to enlarge theaperture of the second scene and can comprise a plurality of opticalcomponents.

The wide angle imaging assembly of the invention can further comprise aconically shaped hole extending along the vertical axis of symmetry fromthe upper surface to the lower surface and a black cone designed toprevent glare compatibly shaped to be placed inside the hole.

The wide angle imaging assembly of the invention can further comprise aholding element that is fabricated together with and as part of theoptical block. The holding element is located adjacent to the lowersurface and extends downwards. The holding element does not interferewith or block the rays that exit from the lower surface. The holdingelement can have the shape of a tube made of an optically transparentmaterial.

The wide angle imaging assembly of the invention may further comprise amechanical connector having a first edge and a second edge. The firstedge of the connector can be designed to connect to the holding element.The second edge of the connector can be designed to connect to an imagecapture device, such that the image capture device is positionedcoaxially with the optical block, facing the block's lower surface. Themechanical connector may further comprise optical lenses positionedcoaxially with the optical block and designed to enhance the quality ofthe images exiting the lower surface of the optical block. The secondedge of the connector can be designed to connect to an illuminationsource so that it positions the illumination source adjacent to theexterior edge of the holding element.

The wide angle imaging assembly of the invention can further comprise animage capture device designed to capture images that arrive from theoptical block. The spectral range, to which the image capture device issensitive, is at least partially identical to the specific spectralrange to which the optical block is transparent.

The wide angle imaging assembly of the invention can further comprise anillumination source that distributes illumination rays, which travelthrough the holding element and are distributed by the surfaces of theoptical block. The wavelength of the illumination source is within therange of the specific spectral range to which the optical block istransparent. The wide angle imaging assembly can comprise a plurality ofillumination sources, capable of emitting more than one wavelength. Allof the illumination wavelengths are within the specific spectral rangeto which the optical block is transparent.

In another embodiment the wide angle imaging assembly of the inventioncan further comprise:

-   -   a. An axi-symmetric lens, capable of reflecting a second        panoramic scene, which is at least partially included in the        first scene. The axi-symmetric lens is positioned coaxially with        and above the optical block.    -   b. A hole extending along the vertical axis of symmetry of the        optical block.    -   c. An optical assembly located within the hole comprising at        least a prism or reflective surface. The prism or reflective        surface designed to refract or reflect light rays that are        reflected by the axis-symmetric lens.    -   d. A compatibly positioned image capture device

The axi-symmetric lens is capable of transmiting light rays in a secondspectral range which is at least partially different than the specificspectral range to which the optical block is transparent. The opticalassembly does not interfere or block the rays reflected from the opticalblock. The first panoramic scene provided by the optical block in thespecific spectral range is at least partly identical to the panoramicscene provided by the axi-symmetric lens in the second spectral range.

All the above and other characteristics and advantages of the inventionwill be further understood through the following illustrative andnon-limitative description of preferred embodiments thereof, withreference to the appended drawings. It is stressed that the particularsshown are by way of example and for purposes of illustrative discussionof preferred embodiments of the present invention only. No attempt ismade to show in the drawings structural details of the invention ingreater detail than is necessary for understanding of the invention.Skilled persons will readily understood details not shown in the figureswill easily appreciate how the several embodiments of the invention maybe carried out.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematically an embodiment of an aspheric optical blockthat provides coverage of a panoramic scene;

FIG. 2 shows schematically another embodiment of an aspheric opticalblock that provides coverage of a panoramic scene;

FIG. 3 shows schematically another embodiment of an aspheric opticalblock that provides coverage of a panoramic scene, equipped with acomponent for glare reduction;

FIG. 4 shows schematically an embodiment of an aspheric optical blockthat provides coverage of a nearly spherical scene;

FIG. 5 shows schematically an optical structure that enables coverage ofa nearly spherical field of view;

FIG. 6 shows schematically another optical structure that enablescoverage of a nearly spherical field of view;

FIG. 7 shows schematically an optical structure also used fordistribution of illumination to a panoramic scene;

FIG. 8 shows schematically an illumination conductor used to conduct theillumination from an illumination source to the optical block;

FIG. 9 shows schematically an optical structure also used fordistribution of illumination to a nearly spherical scene;

FIG. 10 shows schematically an optical block, equipped with anadditional optical component and also used for distribution ofillumination to a nearly spherical scene;

FIG. 11 shows schematically another optical block equipped with anadditional optical component and also used for distribution ofillumination to a nearly spherical scene;

FIG. 12 shows schematically yet another possible design of an opticalblock that enables both coverage and illumination of a nearly sphericalscene;

FIG. 13 shows schematically methods of combining additional componentsin the optical system that enable enhanced image quality and/orcomponents that provide higher strength to the optical system; and

FIG. 14 shows schematically two omni-directional optical systems thatenable imaging of the perimeter scene at two different wavelengthssimultaneously.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiments of the present invention are describedhereinbelow with reference to the figures. All of the figures show across-sectional view of only the main optical components of anelectro-optical system. The system is designed to produce an image of acylindrical or nearly spherical field of view. The main opticalcomponents, which are shown, are generally those that are responsiblefor gathering the light rays from the cylindrical or nearly sphericalfield of view at the same instant, and directing those light rays to theother components of the system. As it is clear that several differentcomponents comprise the entire electro-optical system, reference to onlythe main optical components is made for the sake of brevity and sinceother components and their incorporation in the system are known fromthe prior art and are well within knowledge of those skilled in the art.The figures are schematic and designed to provide a general perceptionof preferred embodiments of the present invention. In some of thefigures are shown optical paths of light rays that travel through theoptical system. These paths are schematic and they are shown in order tomake apparent the course of refraction and/or reflection of the rays bythe main optical components of the system. In all of the figures thereis shown a solid axi-symmetric optical lens, which is responsible forthe actual direction of the surrounding scene towards an image capturedevice or towards other optical components. The solid axi-symmetricoptical lens is referred to as the “main lens”. Several differentembodiments are described in order to demonstrate the variety of designsand different types of information that can be obtained by use of thedifferent embodiments of the invention. The main lens is produced byknown optical fabrication methods such as diamond turning, molding etc.and the material of which the block is produced is selected to enableoptical transmittance of a specific spectral range. All of theembodiments of the imaging assembly of the invention comprise a mainlens made from an aspheric optical block comprising the following:

-   -   a. A vertical axis of symmetry;    -   b. A transparent upper surface, at least part of which is        capable of reflecting rays that hit it from the inner side of        the optical block.    -   c. A transparent perimeter surface; and    -   d. A transparent lower surface.

In all embodiments, light rays of the specific spectral rangeoriginating in a first scene having a 360 degrees panoramic perimeterare refracted by the transparent perimeter surface, enter the asphericblock, are then reflected by the upper surface towards the transparentlower surface, are then refracted by the transparent lower surface, andexit the main lens through the transparent lower surface.

It is stressed that besides the main lens, additional components arerequired to make best benefit of the present invention. Those additionalcomponents, may include, but are not limited to:

-   -   a. An image capture device, located, directed, and set in a        manner that enables the capture of an optimal image that is        produced by the main lens. In preferred embodiments of the        present invention, the image capture device is located coaxially        with the main lens. The image capture device is preferably        equipped with a focusing lens, set to capture a focused image        depending on the distance of the image capture device from the        main lens.    -   b. Prisms, which are capable of directing the image that is        produced by the main lens towards an image capture device, which        (in some embodiments) is not located coaxially with the main        lens.    -   c. Correcting lenses, which may be used to enhance the quality        of the image before it is captured by the image capture device.        Those correcting lenses are generally positioned between the        main lens and the image capture device, and they are selected,        designed and positioned as a function of the design of the main        lens. The necessity of using correcting lenses may be reduced to        a minimum by proper optical design of the main lens in order to        reduce astigmatism, aberrations and other optical distortions of        light rays to a minimum.    -   d. A processing unit that receives, processes, and displays the        image that is captured by the image capture device.

In FIG. 1 is schematically shown a preferred embodiment of the presentinvention. In this figure there is shown a design of a main lens (1)that provides a reflection of the perimeter around it and enables thecapture of the entire perimeter at the same instant by a suitable imagecapture device (not shown). The main lens (1) comprises a transparentperimeter surface (2), a transparent upper surface (3), a transparentlower surface (4) and a holding element (5). All of the mentionedsurfaces are fabricated as part of a unified mold, or single solidoptical component. In a preferred embodiment of the present invention,the upper transparent surface (3) is coated with reflective material onits exterior surface, enabling reflection of light rays that arrive fromthe direction of the inner side of the main lens (1).

Reference is now made to schematic optical paths of light rays thattravel through the main lens (1). A first light ray (6), originating inthe field of view that is covered by the main lens (1), penetrates themain lens's transparent perimeter surface (2), where it is refracted.The ray (6) then travels through the solid medium of the main lens (1)and is incident upon the inner side of the upper surface (3). As aresult of the reflective coating on the exterior of the upper surface(3), the ray (6) is then reflected towards the lower transparent surface(4), where it is refracted again and exits the main lens (1). Light ray(7) travels a similar optical path, being refracted and reflected by thesame surfaces as ray (6).

According to another preferred embodiment of the present invention, theupper surface (3) may remain entirely or partly uncoated. In this case,the light rays, which hit the upper surface (3) from the inner side ofthe main lens (1), are reflected according to Snell's Law of TotalInternal Reflection. Those skilled in the art will appreciate that bynot using a reflective coating, and leaving a part (or all) of the uppersurface (3) uncoated, a different field of view may be covered by themain lens (1). Therefore the choice of whether or not to use areflective coating depends on the requirements of the specificapplication, and the design of the main lens.

It is further stressed that the exact shape of the main lens's surfacesis not random, and each surface is designed according to the desiredfield of view to be covered, the required angular resolution, andadditional parameters which are known to those skilled in the art. Eachsurface's design is affected by the design of the other surfaces,therefore the design is done by constantly considering the mutual affectthat each surface has on the field of view which is covered, chromaticor other aberrations and/or distortions that might be caused to lightrays along their path etc.

It is preferable to fabricate the main lens together with a holdingelement (5), which is also a part of the unified mold, in a shape thatenables direct connection of the main lens (1) to an image capturedevice, or other mechanical component or connector.

In FIG. 2 is schematically shown a second preferred embodiment of themain lens (8). This embodiment also includes a transparent perimetersurface (9), a transparent upper surface (10), a lower surface (11) anda holding element (12). Perimeter surface (9) is a negative opticalsurface that enables the capture of a larger vertical field of view thanthat captured by the embodiment of the main lens shown in FIG. 1. Twolight rays, (13) and (14) represent schematic optical paths of lightrays that travel through the main lens (8). In this embodiment as wellas in that shown in FIG. 1, it is possible to exploit Snell's Law ofTotal Internal Reflection and not to coat all or part of the uppersurface with reflective coating.

In FIG. 3 is schematically shown an embodiment of the imaging assemblyof the invention that incorporates within the main lens an additionalcomponent that reduces glare. In this embodiment, the main lens (15)comprises a hole in its center, extending along its central axis, fromits upper surface (16) to its lower surface (17). The hole is preferablyconically shaped. Inside the hole there is placed a blackened cone (18)that preferably extends through the entire thickness of the main lens(15) and extends downwards below the lower surface (17). The cone (18)is designed to absorb light rays that may be reflected or dispersed toundesired directions and cause glare that is visible in the final image.The undesired glare is a side-affect, which appears in varyingintensities as a function of the optical design of the main lens.Therefore the incorporation of the blackened cone is optional anddependent on the intensity of the glare.

In FIG. 4 is schematically shown an embodiment of a main lens that iscapable of covering a nearly spherical field of view. In this figure themain lens (19) comprises a transparent area (20) located at the centerof the upper surface (21). The transparent area (20) is axi-symmetricand may be fabricated either as a hole, extending from the upper surface(21) downwards to the lower surface (22), or simply as an area of uppersurface (21) which is not coated with reflective material. If a hole isnot implemented, it is possible to fabricate the transparent area (20)as an area having a different curvature than that of the upper surface(21). In this way a lens effect may be achieved simply by proper designof the transparent area's curvature. The presence of transparent area(20) enables coverage of a field of view above the upper surface (21),which is additional to the cylindrical field of view that is generallycaptured by the embodiments described hereinabove. It is possible tocombine additional optical elements (23) coaxially and above thetransparent area (20) that would enable control over the size andoptical qualities of the additional scene that is covered. The form ofthe main lens (19) shown in FIG. 4 enables relatively convenientpositioning of the additional optical components (23) within the nichethat exists above the upper surface (21). However, it is stressed thatthe principles of the method of covering the additional scene, as shownin this figure, are applicable mutatis mutandis to other embodiments ofthe main lens. Each embodiment of the main lens might impose a differentdesign of the optical components (23) and may require mechanicaladaptors or special connection methods of the additional opticalcomponents (23) to the main lens (19). Those connection methods are wellknown to those skilled in the art, and have been presented in prior art,therefore no further reference is made to connection of opticalcomponents amongst themselves.

Reference is now made to optical paths of light rays that travel throughthe main lens (19). Light rays (24, 25), which originate in thecylindrical field of view covered by the main lens (19), travel the samepath as light rays (13, 14) shown in reference to FIG. 1. Light ray(26), which originates in the additional scene, not included in thecylindrical scene, is refracted by the additional optical component(23), if such component is present. The ray (26) then travels towardsthe transparent area (20) where it is refracted again and travelsthrough the main lens (19) until reaching its lower surface (22) whereit exits the main lens (19). An additional light ray (27) travelsessentially the same course as ray (26). Light ray (26) and light ray(27) represent the edges of the additional scene that is covered (i.e.the aperture of the scene). As previously described, the aperture may becontrolled by the selection and/or design of the optical components (23)and/or of the curve of the part of the surface defining the transparentarea (20).

In FIG. 5 is schematically shown another embodiment of main lens thatenables coverage of a nearly spherical field of view. In this embodimentthe main lens (28) comprises a transparent perimeter surface (29), atransparent upper surface (30), a central transparent upper surface(31), a lower transparent surface (32) and a central transparent lowersurface (33). Additionally, the main lens (28) comprises a holdingelement (34). A first light ray (35) represents a light ray thatoriginated within the range of the cylindrical scene (36) that surroundsthe main lens (28) and that is covered by the main lens (28). The lightray (35) is refracted by the perimeter surface (29), travels through thesolid medium of the main lens (28), hits the upper surface (30), isreflected downwards towards the lower surface (32) where it is refractedagain, and exits the main lens (28). A second light ray (37) representsa light ray that originates above the central upper surface (31) in ascene (38) that is covered by the central upper surface (31). The secondlight ray (37) is refracted by the central upper surface (31),penetrates the main lens (28), travels through the lens's solid medium,is refracted by the central lower surface (33), and exits the lens. Alllight rays originating in the cylindrical scene (36) and in theadditional scene (38) together comprise a nearly spherical scene.

In FIG. 5, the central upper surface (31) and the upper surface (30) areshown as having two different curvatures, however, they may befabricated as a single curved surface, depending on the application, thedesired field of view etc. In the same way, the central lower surface(33) and the remainder of the lower surface (32) which are shown ashaving two different curvatures, can be fabricated as a single curvedsurface.

In FIG. 6 is schematically shown yet another embodiment of a main lensthat enables coverage of a nearly spherical field of view. In thisembodiment, the main lens (39) comprises a hole in its center extendingalong its central axis of symmetry from the main lens's upper surface(40) to its lower surface (41). The hole is preferably conically shaped.Inside the hole there is placed an optical assembly (42), which maycomprise one or more optical components packaged together. The opticalassembly is shaped (or packaged in a shape) compatible with the shape ofthe hole, so that it can be inserted and fastened inside the hole. Theoptical assembly (42) is designed to refract rays that originate at ascene that is additional to the cylindrical scene surrounding the axisof symmetry of the main lens (39). A first light ray (43) represents aray that originates in the cylindrical scene and a second light ray (44)represents a ray that originates in an additional scene located abovethe upper surface (40) of the main lens (39). Light ray (43),originating in the cylindrical scene, is refracted by the perimetersurface (45), then reflected by the upper surface (40) towards the lowersurface (41), then refracted by the lower surface (41), and exits themain lens (39). Light ray (44), which originates in the additionalscene, is refracted by the optical assembly (42). The optical assembly(42) may include one or more optical components; therefore, the ray (44)may be refracted more than once, depending on the number of opticalcomponents comprising the optical assembly (42). The rays originating inthe additional scene exit the optical assembly (42) and can be capturedby the same image capture device that is designed to capture the raysthat originate in the cylindrical scene. Therefore the same imagecapture device may capture a nearly spherical scene.

In FIG. 7 is schematically shown an embodiment of the imaging assemblyof the invention that utilizes the form of the main lens (46), which isused for capturing the omni-directional scene, to simultaneouslydistribute illumination to the scene that is to be imaged, thereforeenabling image capture in limited lighting conditions. The main lens(46) is preferably fabricated with a holding element (47). All or partof the structure of the holding element can be utilized as anillumination conductor (47′). Illumination sources (48) may be locatedat the end of the illumination conductor (47′). The light originating atthe illumination sources (48) penetrates the illumination conductor(47′) and travels along the illumination conductor (47′) until reachingthe main lens (46). The illumination rays travel through the solidmedium of the main lens (46), hitting its upper surface (49) andreflected by it towards the perimeter surface (50). The illuminationrays are then refracted and exit the main lens (46) thus illuminatingthe scene located around the main lens (46). It is stressed that thelength of the holding element (47) may be determined to achieve optimallight conduction. The holding element (47) should be fabricated from amaterial that is transparent to the wavelength/s of light emitted by thesource, thus enabling optimal light conduction from one end of theillumination conductor (47′) to the main lens (46). The illuminationconductor may be fabricated as a tube, which is separate from the mainlens (46), meaning that a separate illumination conductor is connectedto the holding element. The area of connection between the separateillumination conductor and the holding element should enable penetrationof light rays from the illumination conductor into the part of thestreucture of the holding element that functions as the illuminationconductor and from there to the main lens (46). It is stressed that theincorporation of illumination sources in the system does not compromiseits image capture capability. It is further stressed that theillumination source may be chosen to be in one or more differentwavelengths (not necessarily the visible spectrum). However it isimportant to choose the fabrication material according to the spectrumof the illumination source, to ensure that the illumination conductor(47′) and the main lens (46) are transparent to the illuminationwavelengths.

In FIG. 8 is schematically shown an embodiment of the imaging assemblyof the invention comprising means for interfacing an illumination sourcewith the illumination conductor. According to this embodiment, theillumination conductor (51) includes, or is connected to, anopto-mechanical structure (52) at its end. The opto-mechanical structure(52) comprises connention means (53) designed to be connected to theillumination source and a reflective surface (55) designed to reflectthe illumination toward the illumination conductor (51). A light ray(54) originating at an illumination source enters the opto-mechanicalstructure (52), where it is refracted by the reflective surface (55) tothe direction of the illumination conductor (51). From the reflectivesurface (55) the ray (54) travels through the illumination conductor(51) towards the main lens (56) by which it is reflected and refractedto illuminate the scene surrounding the main lens (56).

In FIG. 9 is schematically shown an embodiment of a main lens that canbe used with a light source to illuminate a nearly spherical scene.According to this embodiment, the upper surface (57) of the main lens(58) is not covered with a reflective coating at all; or, alternately,only a part of the upper surface (57) is coated with a reflectivecoating. Light rays (59) originating at a light source (60) travelthrough the illumination conductor (61) until reaching the main lens(58). At the top of the illumination conductor (61) the light rays aredispersed and are incident upon the inner side of the upper surface (57)of the main lens (58) from many different angles. The light rays thatare created after hitting the upper surface (57) can be divided intothree groups. The first group of rays, represented by light ray (62) isreflected by the upper surface (57) towards the perimeter surface (63).The reflection is either from a reflective coating which coats the uppersurface or by total internal reflection, if this is made possible by thespecific design of the main lens (58). The ray (62) then hits theperimeter surface (63) where it is reflected again towards a differentarea of the upper surface (57). The reflection by the perimeter surfaceresults from either reflection from a reflective coating applied to anarrow strip of the perimeter surface or by total internal reflection,if possible. The ray (62) then hits the upper surface (57) and isrefracted by it, exiting the main lens (58) and illuminating a part ofthe scene located above the upper surface (57). It is easily understoodthat, in order to enable the exit of the first group of light rays fromthe upper surface (57), the specific area in the upper surface fromwhich the first group of rays is designed to exit, must remaintransparent (uncoated).

A second group of light rays, represented by ray (64) and ray (65), isreflected by the upper surface (57) towards the perimeter surface (63).The rays (64, 65) are refracted by the perimeter surface (63) and exitthe main lens (58), illuminating a scene located around the axis ofsymmetry of the main lens (58).

A third group of light rays, represented by ray (66) and ray (67), isrefracted by the upper surface (57) and exits the main lens (58)illuminating the part of the scene which is located above the uppersurface (57). In order to enable the third group of rays to exit theupper surface (57), the area of the upper surface, from which the raysare designed to exit, must remain transparent (uncoated).

It is stressed that the division into the three groups of light raysdescribed hereinabove may not be applicable to all forms of the mainlens. The exact paths the light rays will take is dependant on the angleof total internal reflection and additional parameters such as whicharea/s is/are coated with reflective coating, the exact shape of andrelation between the surfaces of the lens, etc. The purpose of FIG. 9 isto schematically describe the three possible principle groups of lightrays that pass through the main lens.

In FIG. 10 is schematically shown another embodiment of the main lenscomprising a transparent optical dome (68) that is connected to the mainlens (69). The dome (68) may serve several possible functions. A firstfunction served by the dome (68) can be to evenly disperse light rays(70) that are provided to illuminate the scene above the dome (68).Light rays (70) exiting the main lens (69) will hit the dome (68) and bedispersed by it to evenly illuminate the scene which is located abovethe dome (68), thus enabling a clear and glare-free view of the scene. Asecond possible function of the dome (68) is to complete the structureof the main lens (69) to form an ergonomic structure that will enablesmooth and easy insertion of the main lens to body cavities, when themain lens (69) is incorporated in a medical device, designed to imageinner body canals, or into other cavities in non-medical applications. Athird possible function of the dome (68) is to push away any liquids orsolid objects (e.g. body tissue in medical applications) that may stickto the main lens (69) and/or obscure its field of view.

In FIG. 11 is schematically shown another embodiment of the main lensthat provides illumination and imaging of a nearly spherical field ofview. In this embodiment, an optical structure (71) is incorporatedabove the central upper surface (72) of the main lens (73). The opticalstructure (71) is designed to enlarge the aperture of the scene locatedabove the central upper surface (72) which is covered by the main lens(73) and which is not part of the cylindrical scene surrounding its axisof symmetry. A light ray (74), representing light rays that originate inthe field of view covered by the optical structure (71), is refracted bythe optical structure (71) towards the central upper surface (72), thenrefracted again and travels through the main lens (73) until exiting themain lens from its central lower surface (75). An embodiment of the mainlens (73), which does not include the optical structure (71), wasdescribed with reference to FIG. 5 hereinabove. Comparing the embodimentshown in FIG. 5 with that shown in FIG. 11, it can be seen that theabsence of the additional optical structure (71) causes the field ofview covered by the central upper surface to be narrower than the onecovered with its presence.

In FIG. 11, ray (76) represents rays originating in the cylindricalscene surrounding the axis of symmetry of the main lens (73). The ray(76) takes a similar path to that shown in previous figures for raysoriginating in the cylindrical scene. It is stressed that theincorporation of the optical structure (71) does not interfere with thepath of light ray (76) or with its reflection by the upper surface (77).

Ray (78) represents a light ray designed to illuminate a scene locatedabove the central upper surface (72). It is stressed that theincorporation of the optical structure (71) does not interfere with thepath of light ray (78), nor does it block light ray (78) from the scenethat it is intended to illuminate.

In FIG. 12 is schematically shown an embodiment of the main lens thatprovides both coverage and illumination of a nearly spherical field ofview. The form of the main lens in this embodiment is ergonomicallyshaped to enable easy and smooth insertion into, for example, bodycanals when the main lens is incorporated into a medical device. In theembodiment shown in FIG. 12, the main lens (79) has a perimeter surface(80) that extends upwards as compared to that of the embodimentsdescribed hereinabove. The perimeter surface is preferably extended in acircular manner to create the unique ergonomic shape withoutcompromising the optical qualities of the lens. The main lens (79)comprises a transparent perimeter surface (80), a transparent uppersurface (81) preferably coated with reflective material on its exteriorside, a transparent central upper surface (82), and a transparent lowersurface (83), which may be comprised of one or more axi-symmetriccurves. Additionally, the main lens comprises a holding element (84),whose length can be determined according to its purpose. The holdingelement can be used also as an illumination conductor.

A light ray (85) originating in the cylindrical scene (86) that surroundthe axis of symmetry of the main lens (79) is refracted by thetransparent perimeter surface (80), enters the solid medium of the mainlens (79), is reflected by the upper surface (81) towards the lowersurface (83), where it is refracted again and exits the main lens (79).A light ray (87) originating in an additional scene (88), located atleast partially above the cylindrical scene (86) is refracted by thecentral upper surface (82), penetrates the main lens (79), travelsthrough the solid medium of the main lens (79) towards the lower surface(83), where it is refracted and exits the main lens (79). Light rays(89, 90) originating at an illumination source (91) travel through theillumination conductor (84), enter the main lens (79), are reflected bythe upper surface (81) towards the perimeter surface (80) where they arerefracted and exit the main lens (79), thus illuminating the cylindricalscene (86). Another light ray (92) originating at the same illuminationsource (91) takes a different optical path within the main lens (79) andis directed to illuminate the additional scene (88). To cause the lightray (92) to illuminate the additional scene (88), parts of the perimetersurface (80) can be coated with reflective material. Any such coating ofthe perimeter surface (80) does not compromise the coverage of thecylindrical scene (86), and is applied in an area (92), which is out ofthe range that covers that scene (86). All of the light rays discussedin the previous paragraph pass through the main lens (79)simultaneously, thus it is possible to image a nearly spherical scene,which comprises the cylindrical scene (86) and the additional scene(88), and at the same time to illuminate both scenes. Therefore, imagingof a nearly spherical scene is possible also in dark environments, forexample in the inner canals of the body during medical endoscopyprocedures, or in the interior of an engine.

In FIG. 13 is schematically shown an embodiment of the main lens thatincorporates additional components in its holding element. In thisembodiment, the main lens (93) is fabricated with, or connected to, aholding element (94), which can be also used as an illuminationconductor as has been described hereinabove. The holding element istube-shaped, therefore it is possible to insert inside it optical ormechanical components that will assist the overall performance of theoptical system. For example, a blackened tube (95) may be inserted incontact with the inner wall of the holding element (95). The purpose oftube (95) is either to provide mechanical strength to the holdingelement (94) and/or to prevent glare that may be caused by light raysfrom the illumination source that exit through the transparent sides ofthe holding element (94). The tube (95) may also incorporate additionaloptical lenses (96,97), which are designed to enhance the quality of theimage that exits the main lens (93).

In FIG. 14 is schematically shown an embodiment of the inventionincorporating, in addition to the main lens, an additional optical lensthat is also capable of covering at least a cylindrical field of view.This embodiment enables imaging of the perimeter scene at two differentwavelengths. A first main lens (98) is made as a solid mold comprising atransparent perimeter surface (99), an upper transparent surface (100),preferably coated with reflective material from its exterior, a lowertransparent surface (101) and a holding element (102). Additionally, themain lens (98) comprises a hole in its center, extending along itscentral axis of symmetry from its upper surface (100) to its lowersurface (101). The hole is preferably conically shaped. Inside the holethere is placed an optical assembly (103). Coaxially with the main lens(98) and above it, there is placed an additional lens (104), which iscapable of providing a reflection of at least the cylindrical scenearound it. The additional lens (104) may be either a lens similar to oneof the embodiments of the main lens described hereinabove or anyaxi-symmetric reflective surface or other type of suitable lensdescribed in the prior art. The additional lens (104) is affixed to themain lens (98) with a suitable mechanical structure (105) that does noteven minimally obscure the perimeter scene from the lens (104).

In the embodiment shown in FIG. 14, two image capture devices are used.A first image capture device (not shown) is designed to capture theimage reflected by the main lens (98). A second image capture device(not shown) is designed to capture the image reflected by the additionallens (104). The two image capture devices are preferably sensitive todifferent wavelengths, compatible with the wavelength sensitivity of thelenses (98, 104). For example, the image capture device designed tocapture the image reflected from the main lens (98) could be sensitiveto the visible spectrum and the image capture device designed to capturethe image reflected from the additional lens (104) could be sensitive tothe near infra red spectrum. Those skilled in the art will understandthat it is possible to control the wavelength sensitivity of the lenses(98, 104) by proper selection of the lenses material or the selection ofthe reflective coating used to coat the lenses.

A description of the optical paths of various light rays that travelthrough the system will now be given. A first group of light rays (106,107) represent light rays that originate in the field of view covered bythe main lens (98). These light rays (106, 107) are refracted by theperimeter surface (99), reflected by the upper surface (100) towards thelower surface (101) where they are refracted again and exit the mainlens (98), and captured by a first image capture device (not shown)designed and set to capture the image that is reflected by the main lens(98).

A second group of light rays (108, 109) originating in the scenesurrounding the additional lens (104), are refracted and reflected atthe surfaces of the additional lens (104) and penetrate the opticalassembly (103) located coaxially with additional lens (104). Inside theoptical assembly (103) there is located at least a prism or reflectivesurface (110) designed to direct the rays reflected by the additionallens (104) to the second image capture device (not shown). As part ofthe optical assembly (103) there may be incorporated additional opticalcomponents that will enhance the quality of the image reflected by theadditional lens (104).

It can therefore be seen that each of the two image capture devicesacquires a different image. As previously stated, it is preferable thateach image is in a different wavelength range. Thus it is possible tocombine in the same system, two sub-systems that enable, for example,omni-directional imaging both in full lighting and in limited lightingconditions.

Proper optical design of the two lenses (98, 104) enables control overthe vertical field of view of the cylindrical scene covered by each ofthe lenses.

Although embodiments of the invention have been described by way ofillustration, it will be understood that the invention may be carriedout with many variations, modifications, and adaptations, withoutdeparting from its spirit or exceeding the scope of the claims.

1. A wide-angle imaging assembly comprising a main lens produced from anaspheric optical block, said aspheric optical block having: a. Avertical axis of symmetry; b. A transparent upper surface, at least partof which is capable of reflecting rays that impinge upon it from theinner side of said optical block; c. A transparent perimeter surface;and d. A transparent lower surface; wherein the fabrication material ofsaid optical block is selected to enable optical transmittance of aspecific spectral range; and wherein light rays in the specific spectralrange originating in a first scene having a 360 degrees panoramicperimeter are refracted by said transparent perimeter surface, entersaid optical block, are then reflected by said upper surface towardssaid transparent lower surface, are then refracted by said transparentlower surface, and exit through said transparent lower surface.
 2. Awide angle imaging assembly according to claim 1, wherein the uppersurface is at least partially, axi-symmetrically coated with reflectivematerial on its exterior side, thus causing reflection of light raysthat impinge upon it from the inner side of the optical block.
 3. A wideangle imaging assembly according to claim 2, wherein the reflectivematerial that coats the upper surface is selected to enable reflectionof light rays in the specific spectral range transmitted by the materialof the optical block.
 4. A wide angle imaging assembly according toclaim 1, further comprising a transparent area in a part of the uppersurface around the vertical axis of symmetry, enabling light from asecond scene, located at least partially above the first scene, to passthrough said transparent area and travel through the optical block andexit said block.
 5. A wide angle imaging assembly according to claim 4,wherein the curvature of the surface of the transparent area isdifferent than the curvature of the remainder of the upper surface.
 6. Awide angle imaging assembly according to claim 4, wherein the lowersurface is described by two different axi-symmetric curves.
 7. A wideangle imaging assembly according to claim 4, wherein the transparentarea is fabricated as a hole extending along the vertical axis ofsymmetry.
 8. A wide angle imaging assembly according to claim 7, whereinthe hole extends from the upper surface to the lower surface.
 9. A wideangle imaging assembly according to claim 8, wherein the shape of thehole is conical.
 10. A wide angle imaging assembly according to claim 7,further comprising an optical structure placed within the hole; saidoptical structure designed to enhance or correct light rays coming fromthe second scene.
 11. A wide angle imaging assembly according to claim10, wherein the optical structure placed within the hole comprises aplurality of optical components.
 12. A wide angle imaging assemblyaccording to claim 4, further comprising an optical structure locatedabove the transparent area and coaxially with it; said optical structuredesigned to enhance or correct light rays coming from the second sceneor enlarge the aperture of said second scene.
 13. A wide angle imagingassembly according to claim 12, wherein the optical structure locatedabove the transparent area comprises a plurality of optical components.14. A wide angle imaging assembly according to claim 1, furthercomprising: a. A hole which is conically shaped, extending along thevertical axis of symmetry from the upper surface to the lower surface;and b. A black cone compatibly shaped to be placed inside said hole,wherein said cone is designed to prevent glare.
 15. A wide angle imagingassembly according to claim 1, further comprising a holding element,fabricated together with and a part of the optical block, said holdingelement located adjacent to the lower surface and extending downwards,wherein said holding element does not interfer with or block the raysthat exit from said lower surface.
 16. A wide angle imaging assemblyaccording to claim 15, wherein the holding element is shaped as a tubemade of an optically transparent material.
 17. A wide angle imagingassembly according to claim 15, further comprising a mechanicalconnector having a first edge and a second edge; where said first edgeof said connector is designed to connect to the holding element.
 18. Awide angle imaging assembly according to claim 17, wherein the secondedge of the connector is designed to connect to an image capture device,positioning said image capture device coaxially with the optical block,facing the lower surface of said block.
 19. A wide angle imagingassembly according to claim 17, wherein the mechanical connector furthercomprises optical lenses positioned coaxially with the optical block anddesigned to enhance the quality of the images exiting the lower surfaceof said optical block.
 20. A wide angle imaging assembly according toclaim 17, wherein the second edge of the connector is designed toconnect to an illumination source, positioning said illumination sourceadjacent to the exterior edge of the holding element.
 21. A wide angleimaging assembly according to claim 18, further comprising an imagecapture device designed to capture images that arrive from the opticalblock, wherein the spectral range to which said image capture device issensitive, is at least partially identical to the specific spectralrange to which the optical block is transparent.
 22. A wide angleimaging assembly according to claim 20, further comprising anillumination source that distributes illumination rays, which travelthrough the holding element and are distributed by the surfaces of theoptical block, wherein the wavelength of said illumination source iswithin the range of the specific spectral range to which said opticalblock is transparent.
 23. A wide angle imaging assembly according toclaim 22, comprising a plurality of illumination sources, capable ofemitting more than one wavelength, wherein all of said illuminationwavelengths are within the specific spectral range to which the opticalblock is transparent.
 24. A wide angle imaging assembly according toclaim 1, further comprising: a. An axi-symmetric lens, capable ofreflecting a second panoramic scene, which is at least partiallyincluded in the first scene; said axi-symmetric lens being positionedcoaxially with and above the optical block; b. A hole extending alongthe vertical axis of symmetry of said optical block; c. An opticalassembly located within said hole, said optical assembly comprising atleast a prism or reflective surface designed to refract or reflect lightrays that are reflected by said axis-symmetric lens; and d. a compatiblypositioned image capture device, wherein said axi-symmetric lens iscapable of transmitting light rays in a second spectral range which isat least partially different than the specific spectral range to whichsaid optical block is transparent; said optical assembly does notinterfere or block the rays reflected from said optical block; and saidfirst panoramic scene provided by said optical block in said specificspectral range is at least partly identical to the panoramic sceneprovided by said axi-symmetric lens in said second spectral range.